Paintball

[The Flounder]

Originally Posted by DSA

Given the known characteristics of the FSR I would think a rifled insert "freak" length or greater would be more than sufficient to induce the desired rate of spin. The rest of the barrel being smooth bore shouldn't have much of a negative impact on the already spinning round. If this works imagine the possibilities?? FSR Inserts for your favorite barrel! Ty I have just the barrel for this project

Hammerhead called that the widow maker.

[russc]

There's no need to spin the entire barrel. Just create a small rotating breech section and heavily overbore the barrel in front of it. It could be under 1" long and still be effective.

Air efficiency should not be a major concern with First Strikes. You could butt the rotating breech up against the barrel, with a small gap, revolver style. Four skate bearings on the underside, with a belt pulling the breech down into them, fed by an electric motor. Using a motor would allow for tweaking of the RPM to figure out what works best.

Spinning up the entire barrel seems like a waste to me, and I don't like the idea of rifling because it damages the projectiles.

We aren't dealing with lead bullets. FSRs don't react well to being forced down a tight tube, and we don't have to worry about containing massive pressure spikes, so there's no harm in breaking the barrel into two components.

[uv_halo]

Originally Posted by russc

There's no need to spin the entire barrel. Just create a small rotating breech section and heavily overbore the barrel in front of it. It could be under 1" long and still be effective.

This assumes that there will be no spin loss as the round travels down the overbore due to bumps against the I.D. (I know they don't make contact with a .75" I.D. I don't know about anything tighter).

...Spinning up the entire barrel seems like a waste to me, and I don't like the idea of rifling because it damages the projectiles.

We aren't dealing with lead bullets. FSRs don't react well to being forced down a tight tube, and we don't have to worry about containing massive pressure spikes, so there's no harm in breaking the barrel into two components.

Where does this statement come from (I'm not blaiming you particularly russc, I see it a lot and it makes me wonder)?

People started asserting this before the rounds were commonly available, and before anyone had a rifled barrel. (I even believed it at one point before I found the skirts to be narrower than the equator).

Now, granted that I was the first one to post up problems of barrel fouling and jams in the LAPCO/Tiberius Barrel but, I've not seen any, I repeat, any damage to the rounds that I could attribute to the LAPCO/Tiberius rifled barrels. I've had just as many rounds fail upon exiting the .690 smoothbore as I've had exiting the rifled barrel. I attribute this to the feed design.

To try and investigate this more directly, I fired a sample of eight rounds (I know, I should've done more) into a bathtub full of water, I retrieved the rounds, and examined them closely:

• One round made it with no damage at all
• One round delivered it's payload (the nose broke completely) but had no damage to the skirt
• Six rounds suffered hairline fractures in the skirt (one of which didn't deliver it's payload)

[russc]

Originally Posted by uv_halo

This assumes that there will be no spin loss as the round travels down the overbore due to bumps against the I.D. (I know they don't make contact with a .75" I.D. I don't know about anything tighter).

It doesn't really matter if the round experiences spin loss while it's going down the barrel, since it's shaped to maintain spin once it leaves. With an adjustable RPM motor, you could easily give it enough spin to match the round's natural rotation at full velocity.

I'd also expect any loss in accuracy from bouncing around an overbored barrel to be marginal, on the scale of improper trigger pull technique.

Where does this statement come from (I'm not blaiming you particularly russc, I see it a lot and it makes me wonder)?

People started asserting this before the rounds were commonly available, and before anyone had a rifled barrel. (I even believed it at one point before I found the skirts to be narrower than the equator).

Now, granted that I was the first one to post up problems of barrel fouling and jams in the LAPCO/Tiberius Barrel but, I've not seen any, I repeat, any damage to the rounds that I could attribute to the LAPCO/Tiberius rifled barrels. I've had just as many rounds fail upon exiting the .690 smoothbore as I've had exiting the rifled barrel. I attribute this to the feed design.

I'll admit I haven't used the factory rifled barrels - I'm speaking from experiences with FSRs getting stuck or having velocity fluctuations in match bored and underbored barrels. Drag has a huge effect on FSRs since they don't deform, causing inconsistency or even failures to fire. Rifling necessitates a tight squeeze on the rounds, and the same thing can be achieved with an overbore+rotating breech, which would be much less liable to have consistency and jamming issues.

That said, rifling has its own appeal as a low tech standalone solution that can be adapted across many platforms. I get it. I just don't think it's an ideal solution if we're starting from scratch.

[DSA]

Originally Posted by russc

There's no need to spin the entire barrel. Just create a small rotating breech section and heavily overbore the barrel in front of it. It could be under 1" long and still be effective.

Air efficiency should not be a major concern with First Strikes. You could butt the rotating breech up against the barrel, with a small gap, revolver style. Four skate bearings on the underside, with a belt pulling the breech down into them, fed by an electric motor. Using a motor would allow for tweaking of the RPM to figure out what works best.

Spinning up the entire barrel seems like a waste to me, and I don't like the idea of rifling because it damages the projectiles.

We aren't dealing with lead bullets. FSRs don't react well to being forced down a tight tube, and we don't have to worry about containing massive pressure spikes, so there's no harm in breaking the barrel into two components.

.

What do you think of this idea amigo?

[russc]

Ah, well, I don't think that would give the rounds much spin since it would just sit still. If the barrel or breech isn't spinning up, then you'll need a full length of rifling.

[uv_halo]

Originally Posted by russc

I'll admit I haven't used the factory rifled barrels - I'm speaking from experiences with FSRs getting stuck or having velocity fluctuations in match bored and underbored barrels. Drag has a huge effect on FSRs since they don't deform, causing inconsistency or even failures to fire. Rifling necessitates a tight squeeze on the rounds, and the same thing can be achieved with an overbore+rotating breech, which would be much less liable to have consistency and jamming issues.

That said, rifling has its own appeal as a low tech standalone solution that can be adapted across many platforms. I get it. I just don't think it's an ideal solution if we're starting from scratch.

The LAPCO/Tiberius model does put a somewhat tight squeeze on rounds. Enough that you cannot blow it through but, not so much you can't push one through with a stick squeegie. The biggest problem with this particular barrel design is fouling but, I found it to have a minimal (read: unnoticable) impact until after about 80rounds fired. The Hammerhead barrels use a looser design but, there's a lot of folks who claim to get a benefit (I'm waiting for testing to confirm these claims) withouth the fouling.

I think a pre-spinning system has some merit but, I wonder if it will bring enough of an improvement to justify the cost to develop a fieldable product.

The unfortunate part of the Tiberius gun design is that the bolt return spring is held in by the barrel so, if you pull the barrel on the field to run a pull through squeegie

[uv_halo]

Originally Posted by DSA

.

What do you think of this idea amigo?

Originally Posted by russc

Ah, well, I don't think that would give the rounds much spin since it would just sit still. If the barrel or breech isn't spinning up, then you'll need a full length of rifling.

I suspect that even in the LAPCO/Tiberius barrel, there is some slippage as the twist rate between the round and the barrel are different (the barrel has a higher twist rate if I remember correctly).

LAPCO currently makes two lengths of the rifled barrel, I'm hoping that testing reveal whether or not there is a difference between the two lengths.

[Spider!]

Originally Posted by uv_halo

The LAPCO/Tiberius model does put a somewhat tight squeeze on rounds. Enough that you cannot blow it through but, not so much you can't push one through with a stick squeegie. The biggest problem with this particular barrel design is fouling but, I found it to have a minimal (read: unnoticable) impact until after about 80rounds fired. The Hammerhead barrels use a looser design but, there's a lot of folks who claim to get a benefit (I'm waiting for testing to confirm these claims) withouth the fouling.

You know, if you have a rifling land that is close to the projectile, the groove will at least direct the air around the projectile in the correct direction, as opposed to going straight over and letting the fins push in the wrong direction.

If you overbore an FS, you might be better off with a little higher twist rate than the fins on the projectile. On a right bore, it probably doesn't need the extra stress.